Parkinson disease (PD) is a progressive neurodegenerative disorder affecting 3/100 people over the age of 65. There is no cure and etiology is unknown. Medications such as levodopa provide good benefit for a number of years. However, disease progression results in significant disability, poor quality of life, and shortened life expectancy. NET-PD is a consortium of 49 Centre's in the US and Canada comprised of neurologists and research coordinators with expertise in carrying out clinical trials in PD. It has been active since 2003 with the aim of developing a disease modifying treatment for PD. The consortium has already completed 2 futility trials, resulting in the identification of creatine as promising compound. This has led to the initiation of a large simple trial (LS-1). The primary objective was to determine if there is a slowing of clinical decline in PD patients defined by a combination of cognitive, physical, and quality of life measures. Active treatment with creatine is being compared to a placebo control against a background of dopaminergic therapy and usual medical care. Over 1700 patients were enrolled between 2007-2010. The trial will continue for another 3 years until all patients have a minimum of 5 years follow up. Thus, retention is a major thrust of the last 3 years of the trial. At the University of Calgary, we have enrolled 44 patients with 98% retention. As a clinical trial site with over 25 years' experience, we feel confident in being able to ensure trial success, with excellent retention. The investigators and coordinators at the University of Calgary are active members in a number of committees, including data analysis, manuscript writing, and retention strategies. This trial is the largest of its kind in P. If creatine is shown to be neuroprotective, this will be the first compound shown to slow clinical progression in a neurodegenerative disorder. It will change the way we manage PD and bring hope to patients with this incurable disease. Secondly, this is the largest data set of information collected on PD, and is available to all investigators in the consortium. It will provide extensive information on PD.